1. Field of the Invention
The invention relates to animal watering valves and, more particularly, relates to animal actuated valves for use by mice, rats, and other relatively small laboratory animals or commercially raised animals.
2. Discussion of the Related Art
Animal actuated watering valves are well known. One such valve is disclosed in U.S. Pat. No. 5,501,177, which issued to Edstrom on Mar. 26, 1996 (the Edstrom patent). The valve disclosed in the Edstrom patent employs a housing having an inlet and an outlet connected by an elongated longitudinal bore, a valve element located adjacent the inlet, and an elongated actuating lever or valve stem which extends through the bore, which projects out of the outlet, and which, when deflected by an animal, opens the valve element to permit the passage of fluid through the valve housing. A movable elastomeric boot is provided adjacent the outlet to inhibit the animal from stuffing bedding material or other debris into the outlet and thus inhibits the valve from being unintentionally lodged in its open position.
The valve element disclosed in the Edstrom patent includes a head on the valve stem which is resiliently biased against a valve seat by an elastomeric diaphragm. The valve seat takes the form of an elastomeric ring against which a downstream surface of the valve stem head abuts. The diaphragm is formed from a unitary elastomeric element including a central web portion and a cylindrical peripheral portion. The web portion has apertures formed therethrough for the passage of fluid, and also has a recess counterbored into the downstream surface thereof for receiving a head of the valve stem. A downstream end of the outer peripheral portion is clamped in place within the housing, and an upstream, second end engages a shoulder on the valve cap.
The diaphragm disclosed in the Edstrom patent works very well but exhibits some disadvantages. For instance, flow tends to be inconsistent with the direction and/or extent of valve stem deflection because the gap between the head of the valve stem and the valve seat is relatively small—even when the valve stem is deflected its maximum amount. Flow consistency is also reduced by the fact that the outlet ports are located peripherally outboard of the valve stem head, leading to water flow from the ports into the downstream sections of the valve to take the form in distinct streams of unequal volume. In addition, because the entire upstream surface of the valve stem head rests on the diaphragm, the forces required to deflect the valve stem increase exponentially with stem deflection—which can be a hindrance to small or weak animals.
The need therefore has arisen to provide a diaphragm-type animal watering valve having improved flow consistency when compared to existing animal watering valves.
The need has additionally arisen to provide a diaphragm-type animal watering valve that is easier to operate than existing animal watering valves.